I'm with Mrs PC.
if you'd left the mask at home, I could be a bit more understanding, but leaving it 20m away in the car.
Ultimately for the 3m to the table, wearing it, not critical. But a) if they say it's ok not to for 3m, what about the people at the table 6m away? 9m? where is the line? Yes there is a certain amount of public health theatre to it. But the reality is, there is strong evidence that wearing a mask helps those around you, and if more people wear them, generally we'll all be better off.
That all being said. IMHO, the risk is too high to be going to an enclosed space like a pub or restaurant in the first place. Sure sitting in the garden is one thing, but inside. Not acceptable, to me, on my accepted level of risk.
I have a selection of masks, and am actually getting quite acclimatised to wearing them. At a physio appointment this week, while wearing a mask, I was doing squats with 55kg, without any noticeable issues with breathing difficulties. For able bodied people, I don't think there are any excuses for not wearing a mask inside. I also think we should aim to be inside as little as possible other than our own homes.
J